1. Field of the Invention
This invention relates to a magnetic disk cartridge comprising a small-diameter, very thin flexible magnetic disk sheet housed in a case and rotated at a high speed for magnetic recording and reproduction. This invention particularly relates to a magnetic disk cartridge provided with an improved liner for removing dust, dirt, or the like from the surface of the magnetic disk sheet.
2. Description of the Prior Art
Floppy disks are widely used as recording media for computers because they are easy to handle and low in cost. The floppy disk comprises a disk-like base made of a flexible polyester sheet or the like, and magnetic material layers overlaid on opposite surfaces of the disk-like base. The floppy disk is rotated at a high speed for magnetically recording information on the magnetic material layers by use of a magnetic head. On the other hand, by utilizing the aforesaid advantages of the floppy disk and the advantage that a magnetic recording medium has over silver halide photographic films in that the magnetic recording medium can be reused, it has been proposed to use a magnetic disk having a size smaller than the size of the floppy disk as an image recording medium in still cameras. The magnetic disk used for still cameras comprises a small-diameter, very thin magnetic disk sheet rotatably housed in a small case. The combination of the magnetic disk sheet with the case is called a magnetic disk cartridge.
In general, the aforesaid magnetic disk cartridge is provided with a liners for removing dust, dirt or the like from the surfaces of the magnetic disk sheet. The liner has heretofore been fabricated of a rayon-polyester mixed nonwoven fabric or the like, and secured to an inner wall surface of the case facing the magnetic disk sheet so that it slightly contacts the surface of the magnetic disk sheet. Therefore, when the magnetic disk sheet is rotated, the whole surface thereof is cleaned by the liner.
However, though the conventional liner fabricated of a nonwoven fabric exhibits a high effect of picking up dust, dirt or the like from the surface of the magnetic disk sheet, it readily releases dust, dirt or the like when the magnetic disk cartridge is subjected to impact. This is because the nonwoven fabric is constituted by fibers thermally fused together, and dust, dirt or the like is merely physically entangled between the fibers. As a result, dust, dirt or the like is readily released by impact from the nonwoven fabric.
Dust, dirt or the like released from the liner and sticking to the magnetic disk sheet cannot immediately be removed by the liner from the magnetic disk sheet. Therefore, particularly in the case of high-density recording on the magnetic disk sheet, drop-out is often caused by dust, dirt or the like.